MECHANICS AND USEFUL AUTS. 19 



pressed an American visitor to the Exhibition, was the barefaceclness 

 and boldness with which machines invented, and even long used in 

 the United States, were brought forward and exhibited as of English 

 origin ; and for which, moreover, prizes and testimonials were sought, 

 and not unfrequently obtained. As mere assertion, however, upon 

 a question like this amounts to but little, we would refer specifically, 

 for illustration and proof, to the English wood-working machinery of 

 the Exhibition ; in which department we unhesitatingly assert there 

 was not a single machine prominently exhibited which was not well 

 known and in use in the United States for five, ten, fifteen, and even 

 twenty years (in one instance) previously. And yet these machines 

 for want of any placard, or of any information in the catalogue to the 

 contrary passed for English inventions, and, in some, bore tickets 

 stating that medals had been awarded to their exhibitors. As an- 

 other illustration bearing more specifically upon this question, we 

 would call attention to the fact that the machine for folding books 

 and newspapers, which was invented, patented, and came into use in 

 the United States previous to 1850, was exhibited the past season in 

 London as a new and original foreign invention, and as such was 

 described, figured, and recommended in leading English journals. 

 Again, the prize-medal threshing machine in the French department 

 was of acknowledged American origin ; a handsomely constructed corn- 

 sheller from Tuscany, the best finished implement shown of Italian 

 construction, was an exact copy of a machine in use in the United 

 States years ago; while in the Prussian department was shown a 

 Wood's reaper, the exact counterpart of which was, at the same mo- 

 ment, on exhibition in the United States department. We are well 

 aware that facts like these will have little of novelty to many American 

 mechanics and engineers ; yet the evidences in the present instances 

 were so pertinent that we could hardly refrain from alluding to them 

 thus publicly. 



Marine Engines. With respect to the comparative character of 

 the marine engines in the Exhibition, the London Engineer says : 

 " The triumph of the screw over the paddle is complete. All the en- 

 gines are direct acting, and the stroke in the largest does not exceed 

 four feet. No new style of engine has been brought forward, but the 

 mechanical skill exhibited in the construction of all receives high 

 praise. The screws for the French engines have edges as sharp as a 

 lady's fan, while the British screws are rounded off at the corners. 

 There can be no question of the fact that by rounding the edges of 

 a screw propeller its useful effect is increased so much as to give an 

 additional speed of from about eleven to twenty-five per cent, to the 

 vessel. One thing very striking and dissimilar between screw and 

 paddle-wheel engines is the very short stroke of the former compared 

 with that of the latter. For example, the new paddle-wheel steamer 

 Scotia, of the Cunard line, has cylinders of one hundred inches in 

 diameter and twelve-foot stroke, while the Achilles, a new gigantic 

 British war screw-steamer, has cylinders one hundred and twelve 

 inches in diameter, and only four-foot stroke." 



Disc-Propeller. A model, bearing this name, was exhibited by the 

 inventor, Mr. Ashton, to illustrate a new method of propulsion. It 

 was simply a common paddle-wheel with the floats removed ; or, to 



